The skier completed the work of 4800J in 5 seconds. How much power did he develop? The 1.3 kW engine

The skier completed the work of 4800J in 5 seconds. How much power did he develop? The 1.3 kW engine ran for 10 minutes. What kind of work did he do? How long will it take for a 450 W winch to do 18 kJ work?

t = 5 s.

A = 4800 J.

N -?

Power N is called a scalar physical quantity, which shows how quickly mechanical work A is performed. Power is determined by the formula: N = A / t, where A is the work performed, t is the time of work.

N = 4800 J / 5 s = 960 W.

Answer: the skier has developed a power of N = 960 W

N = 1.3 kW = 1300 W.

t = 10 min = 600 s.

A -?

N = A / t.

A = N * t.

A = 1300 W * 600 s = 780000 J.

Answer: the engine performed work A = 780,000 J.

A = 18 kJ = 18000 J.

N = 450 W.

t -?

N = A / t.

t = A / N.

t = 18000 J / 450 W = 40 s.

Answer: the winch completed the work in time t = 40 s.